Compressor



june 4, 1935. E. w. swARTwou-r COMPRESSOR Filed May 17, 195s 6 Sheets-Sheet l June 4, 1935. E w. swAR-rwour 2,003,476

COMPRESSOR Filed May 17, 19:55 e sheets-sheet- 2 INVENToR w22/M7.' To NEYS;

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June 4, 1935.

E. W. SWARTWOUT COMPRES SOR Filed May 17, 1955 6 Sheets-Sheet 4 RN 05N IN V EN TOR.

June 4, 1935. E. w. swAR'rwoU'r COMPRE S SOR Filed May 17, 1953 6 Sheets-Sheet 5 COMPRESSOR Filed May 1'7, 1933 6 Sheets-Sheet 6 7 .u 2 mn 9478019680 22 54 ZZRWWHMMN y 7 2 7 5 a, A W3 .a3 3 H .a 2 2 u w .M 3 2 W 2U. 0 uw .an 6 3 2 l 2 2 M 2 All 4W f.. .M2 2 M Ivm f2 s .0/ 6 2 1 2 R W .L M \n 6 6 ...HM 7 N b2 n .fffd o 45N. N022 22u M2 2 Patented J une 4, 1935 yUNITED STATES PATENT oFFIcE 15 Claims.

` clearance volume, to consequently vary inversely the capacity delivered and power required, exactly 'with-variations in demand, by innitesimally small degrees, by an innite number of slight or imperceptably minute additions lor reductions,

lprogressively increasing as by increments, or

progressively decreasing as by decrements, the said supplemental clearance volume, and inversely, the delivered capacity and power, to continuously eiect slight or insensible changes in the .same with changes in demand, all of which may be characterized by gradual slopes or curves.

.Other objects, according to my invention, are to provide capacity varying and regulating means which gradually vary the capacity exactly in accordance with variations in demand within limits ranging from of the full rated normal capacity down to Zero capacity as above described, and vice versa, or, to gradually vary the capacity between the limits of fractional capacities, or, ,by dividing the supplemental clearance volume into fractions of predetermined volumes and by gradually varying one fractional part of the said supplemental clearance volume in periodic cycles to gradually vary the total eective volume of the same and the total supplemental clearance volume over the vfull range of variation, or, to gradually vary the capacity from the full rated capacity down to any predetermined minimum capacity, followed if desired, by complete unloadring to zero capacity.

Also, according to my invention, I provide automatic'v means for continuously controlling and operating the said capacity and power varying means in response to variations in a physical condition such as uid pressure of the air or gas,

or, temperature as in a process.

According t`o my invention, many advantages result from exactly supplying continuous variations in demand by continuously varying the supplemental clearance volume, and therewith the capacity, and required power, to continuously eiect slight or insensible changes, which may be characterized by gradual slopes or curves, .such as true variable capacity, smoothness of operation, efficiency, elimination of sudden changes in torque and load on the motor, elimination of pulsations and surges in the air or gas lines, and in the electric supply lines to the motor operatingthe compressor, as compared with the prior art means which solely and intermittently change 10 the delivered capacity and proportionate power by a limited finite number of steps as by a plurality of means for step by step loading and unloading of a compressor by relatively large predetermined fractional percentages of its full rated .15 capacity, arranged in step by step control, each acting to control a partial loading and unloading of the compressor.

Other objects and features of my invention will be more fully set lforth in the following detailed 20 description and accompanying drawings, in which,-

Figure 1 is a side elevation of one-form of my invention, partially in vertical central section terminating at the inlet and discharge openings. 25

Fig. 2 is a plan viewy taken from Fig. 1, and shows a partial central horizontal section of a compressor cylinder, clearance varying means and interconnecting passages.

Fig. 3 is a side elevation partially in vertical 30 section, and shows one form of clearance varying means and control and regulating means with interconnecting passages.- i

Fig. 4 shows a modication of the arrangement shown in Fig. 3.

Figs. `5 and 'l are side elevations of ,the compressor shown in Figs 1 and 2 and shows one y form of a complete assembly including -a partial vertical section of one form of clearance varying means, electrical operating means, and 'a 40 fluid responsive regulator. Fig. 6 is a detail of a part of the operating means for the clearance varying means shown in Figs. 5 and 7.

Fig. 8 is a detail Vshowing a fluid pressure re- 45 sponsive governor operating an electric switch#` Fig. 9 shows a modied form of supplemental clearance volume control, and Figs. 9 and 10 show details of supplemental clearance volume .which may be used in connection with the con- 50 trol shown in Fig. 11.

Fig. l2 shows a detail of a modified arrangement of the supplemental clearance volume control which may be used in connection with the arrangements shown in other-figures.

and to the frame 4 in accordance with standard.

practise. In the description which follows, reference to bolts obviously needed to bolt together standard parts will not be made. The crank shaft 5 is supported at one end by bearings in the frame 4, and at its opposite end by an outboard bearing in accordance with the usual practise. The motor 6 is mounted directly on the crank shaft 5 and furnishes the power for operating the compressor by way of rotating the crank 1 which is iixedly attached to the .crank shaft 5 with the key 8. The crank pin 9 is also xedly attached to the crank 'I and is rotated by the crank shaft 5. The connecting rod I0 transmits motion from the crank pin 9 to the crosshead I I which reciprocates the piston rod I2 and the attached piston I3. The piston I3 is provided with the usual piston rings I4, and I5 to reduce the leakage vof air or gas past the piston I3 to a minimum as it is reciprocated in the cylinder I.

The inlet pipe opening I6 connects with the chamber I"I from which the inlet stream of fluid to be compressed is divided to alternately pass through the respective inlet passages I8, I9 leading to the inlet valve chambers 20, 2I respectively. The inlet valve 22 is shown positioned in the head plate 2 and held in place by the bonnet 24'and the stud 2.6. 'I'he inlet valve 23 is shown positioned in the head plate 3 and held in place by the bonnet 25 and the stu'd 2l. Preferably,

I employ automatic inlet valves 22, and 23 of the standard plate type of construction which depend for their opening and closing entirely upon pressure differences so as to admit air or gas to the cylinder I through the heads 2, and 3, and to prevent its return from the cylinder I when being compressed.

The discharge valves 28, 29, are also preferably of the standard construction plate type of automatic valves positioned respectively in the heads 2, 3 and retained vin position by the bonnets 3D, 3| and the studs 32, 33, respectively. The dischargevalve 28, connected with the valve chamber 34 and the passage 36, and the discharge valve 29, connected with the valve chamber 35 and the passage 31, join in the compartment 38 to which the discharge pipe 39 is attached. The discharge valves 28, 29, are provided to automatically permit the discharge of compressed air or gas from the cylinder I after its pressure has slightly exceeded that in the discharge line 39, and to prevent its return on the suction stroke of the piston I3. The discharge valve 28 is provided with the seat section 40 and the guide section 4I so as to control its limits of movements when .Opening and closing. The discharge valve 29 is similar in construction to the discharge valve 28. The inlet valves 22, 23 are preferably similar in construction to the discharge valve 28, but positioned so as to operate in reverse direction of travel of fluid to that in the discharge valves 28, 29.

For cooling the parts, I provide the water jacket 42 in the head plate 2, the water jacket 43 in the cylinder I, and the water jacket 44 in the head plate 3. l

When the face 45 of the piston I 3 is at or near its extreme position of travel toward the head plate 2 there will be a space between the piston face 45 and the head plate 2, which together with spaces adjoining the inlet valve 22 and the discharge valve 28 is termed the normal clearance volume at the head end of the cylinder I. Likewise, there will be a clearance volume or space between the face 46 of the piston I3 and thehead plate 3, the inlet valve 23 and the discharge valve 29 when the piston I3 has travelled to its extreme position at the crank end of the cylinder I which is termed the normal clearance volume at the crank end of the cylinder I. In each of these clearance volumes, there remains an unexpelled charge of compressed iluid. after the normal delivery of the compressed fluid has been completed at or near the end of each stroke of the piston I3.

The trapping of some of the compressed fluid in the clearance volumes, when re-expanded to inlet pressure, is equivalent to a certain amount of free air or gas at inlet conditions which is not delivered by the compressor. This re-expansion of the unexpelled compressed iiuid which remained in the clearance volumes consumes a portion of each return stroke of the piston Vbefore the pressure in the cylinder has become reduced to permit the opening of the inlet valves which depend for their opening upon pressure differences. This clearance volume expansion causes a delayed opening of the inlet valves which reduces the quantities sucked into the cylinder to be compressed when compared to the piston displacement or the volume displaced by the net area of the piston. The ratio between net delivery and piston displacement determines the volumetric eiciency of the compressor.

According to well known and well understood equations characterizing the phenomena of the compression of air and gases, the volumetric eniciency of a compressor and consequently the quantity taken in during a suction stroke at standard inlet conditions, depends upon three variables, viz., the ratio of compression, or ratio of the absolute discharge pressure to the absolute inlet pressure, the percentage of clearance, and the exponent of the equation. The exponent is a constant for any particular gas, so it can be disregarded. The ratio of compression is a constant for the condition of constant inlet and discharge pressures. Therefore, only one variable is left, and the volumetric eiliciency, the quantity sucked into the cylinder, and the delivered capacity, vary inversely with variations in the clearance. Increasing the clearance causes a smaller volume to be sucked in, and decreasing the clearance causes a relatively greater volume to be sucked into the cylinder. Also, according to the well known equations, aside from slightly greater possible leakage losses per unit of capacity, hypothetically, the work and horsepower per unit volume of air or gas sucked in, compressed and delivered, is independent of clearance, and varies directly with variations in the quantities sucked in, compressed and delivered, and therefore, with the capacity of the compressor. f

As multi-stage compressors are subject in each stage to all of the characteristics ofsingle-stage compression, the principles of my invention are equally applicable to both single-stage and multistage compressors.

Seldom is any compressor required to deliver continuously any particular fraction of its capacity for any considerable period of time. Hand regulation is not suicient, is expensive and not dependable. A maximum demand for air ,or

CII

gas can be provided for with either one large compressor, or with a number of relatively small compressors, the sum of the capacities of which equal the total maximum demand capacity.` The large single compressor of the conventional prior type with step by step control, and step by step loading. and unloading, effects variations in capacity by relatively large predetermined percentages of its full rated capacity, each acting to control a partial loading and unloading of the compressor the same as if a number of relatively small compressors were-cut into and out of service. Such an arrangement supplies either too much capacity, or not enough capacity, thus causing severe fiuctuations in regulation and in the pressure in the supply and delivery pipes, severe fluctuations in the demand for power, and a relatively high cost of operation,

In the description of the various figures which follow, like numerals denote similar parts, and only one detailed description will be given even though similar parts are frequently repeated in the figures which follow. l

Referring to Figs. 1, 2, and 3, the passage 41 connects the interior of the'cylinder with the supplemental clearance volume represented by the cylinder 49, cooled by the water jacket 50. The passage 48 connects the interior of the cylinder with the supplemental clearance volume represented by the cylinder 5|,v cooled by the water jacket 52. The self operating piston 53, provided with the piston rings 54, 55, is iixedly attached to the rod 56, and reciprocates within the cylinder 49. Likewise, the self operating piston 51, provided with the piston rings 58, 59, is xedly attached to the rod 60, and reciprocates within the cylinder 5|. The piston 53 is provided with the extension 6| to give a damping effect when entering the recess 82 of the head plate 63. The piston 51 is provided with the extension 64 to give a damping effect when entering the recess 65 of the head plate 66. The rod 56 extends beyond the gland 61 of the stuffing box 68, and likewise, the rod 60 extends beyond the gland 69 of the stuffing box 10. The double purpose pistons 53, and 51, are shown respectively in their extreme positions of outward travel thus effecting the maximum available additions of the respective supplemental clearance volumes of the cylinders 49, and 5|, to the normal clearance volumes at the respective opposite ends of the cylinder l. As the piston 53 is moved toward the head 63, the effective volume of the supplemental clearance in the cylinder 49 is gradually reduced until the limit is reached at Zero value of supplemental clearance volume by the closing of the passage 41 with the piston 53 as it approaches the head 63 as a limit of its travel. Likewise, as the piston 51 is moved toward the head 66, the effective volume of the supplemental clearance in the cylinder 5| is gradually reduced until the limit is reached at zero value of supplemental clearance volume by the closing of the passage 48 by the piston 51 as it approaches the head 66 as a limit of its travel.

A pilot valve 1|, provided with the central passage 12, is housed within the body 13, and is operated by the rod 14, which passes through the head 15 which, with the stuing box 16, closes the valve body 13 at its upper end, the lower end of which is closed with the head 11. The lower head 11 of the body 13 is connected with the lower head 18 ofthe cylinder 49 with the pipe 19. Fluid under pressure, such as air or gas may be supplied through the pipe 80 from the discharge pipe 39, or, it may be supplied by the auxiliary operated compressor or liquid pump as at 8|, which may be driven directly from the crank shaft 5, or, by the electric motor 82, energized by the leads 83, 84, and connected to the auxiliary unit 8| by the shaft 85, and both mounted upon the common base plate 86. The unit 8| is supplied with low pressure fluid through the tank 81 and the pipe 88, and the discharge from the unit 8| is connected to the pipe 80 with the pipe 89, and interconnecting ttings as shown. The discharge pipe 89 of the unit 8| may also be connected by the pipe 99 with the pressure tank or accumulator 9| to receive and maintain a supply of excess uid supplied by the unit 8 I, after which, further excess fluid over the normal needs may be discharged through the pipe 92, the relief valve 93, and the pipe 94 to the tank 81. The fioating lever 95 is connected at its one end by the pivoted pin 96 with the rod 56, and intermediate its ends it is connected by the pivotal pin 91, the rod 98, and the pivoted pin 99, with the rod 14, and the pilot valve 1|. By moving the oating lever 95 manually or automatically, `by giving motion` to the pivotally mounted pin about the fulcrum pin 96, the pilot valve 1| is moved accordingly. In the position as shown, the pilot valve 1| is moved to permit a slight flow of fluid from the pipe 80, which flows through the central passage 12 and the pipe 19, to move the piston 53 and its attached rod 56 away from the head 18 in the direction of the head 63 to gradually reduce the supplemental clearance between the piston 53, and the end of the cylinder served by the passage 41, while at thesame time, the rod 56 moves the pivotally mounted pin 96 and this end of the floating lever 95 about its fulcrum pin |00 to close the opening to the pipe 80, and prevent further flow of iiuid from the pipe 80 and to lock the piston 53 in a new position as there is now no flow either into or out of the cylinder 49 through the pipe 19. By lifting the pin |99 and its end of the fioating lever 95, the pilot valve 1| is also lifted, and communication is established between the pipe-19 and the pipes I0 I, |92, and 94, so that the pressure developed in the cylinder by the movement of the piston I3 pushes the piston/53 to cause a movement of the piston 53 toward the head 18, and a flow of fluid through the pipe 19, the valve body 13, and pipes |9|, |92, and 94 to the overflow tank 81, while at the same time, the downward movement of the rod 56, and the pivotally mounted pin 96,-

and this end of the floating lever 95 also lowers the pilot valve 1| and again closes both of the pipes 89, and 0|, thus locking the piston 53 in another new position depending upon the position of the pin |99. Similarly, the pilot valve |93, having the central passage |94 is housed within the valveY body |95 and operated by the rod |06, which passes through the head |01 which, with the stuing box |08, closes the valve body |95 at its upper end, the lower end of which is closed with the head |99. The lower head |09 of the `body is connected with the lower end of the head ||0 of the cylinder 5| with the pipe Fluid under pressure is supplied by the pipe ||2 which connects with the pipe 89, and the overilow, or exhaust, may take place through the pipe ||3 which connects with the pipe |02 and the tank 81. The oating lever ||4 is connected at its one end by the pivotally mounted pin ||5 with the rod 60, and intermediateits ends, -it is connected by the pivotally mounted pinA I I6, therod 'I I1 andthe pivotally. mounted pin,.,||8 'with the rod |06 and the pilot .valve 03.` -By moving the floating lever I i4 manually,

' or automatically, by giving motion to the piv.

otally mounted pin II9 about the'fulcrum pin lI 5, the pilot'valve .|03 is moved accordingly. In the position. as shown, the pilot valve-|03 is moved topermit a slight-flow of uid from the :pipe ||2 which flows through the. central passage |04 'of the pilot valve |03, and the pipeV ||I to move thepiston- 51 and its attached rod 60 away from the head IIO in the direction of the head 66 to gradually reduce the supplemental clearance volume between the piston 51 and the end of the cylinder I served by the passage 48, While at the same time, the rod 60 moves the pivotally mounted pin I|5 and this end of the floating lever II4 about its fulcrum pin I|9 to close the opening to the pipe II2 and prevent further flow from the pipe I I2 and to lock the piston 51in a. new position, as there is now no flow either into, or out of the cylinder 5| through the pipe II I. By lifting the pin II9, and its end of the floating lever |I4, the pilot valve |03 is also lifted, and communication is established between the pipe III and the pipes II3, |02, and 94, so that the pressure developed inthe cylinder I by the movement of the piston I3 pushes the piston 51 to cause a movement oi.' the piston 51 toward the head |I0, and a flow of fluid through the pipe III, the valve body |05, and pipes II3, |02, and 94, to the overflow tank 81,`while at the same time, the downward'movement of the rod 60, and the pivotally mounted pin ||5, and this end of the floating lever II4 also lowers the pilot valve |03 and again closes both of the pipes |I2, II3, thus locking the piston 51 in another new position depending upon the position of the pin |I9. Accordingly, I have provided self operating, double purpose means for controlling the supplemental clearance volume, and for operating the said supplemental clearance volume varying means to gradually Vary the same in one compressioncompartment, land also, in a plurality of compression compartments.

Any suitable physical condition governed means may be employed in connection with the means for regulating and controlling the operation of the supplemental clearance volume gradual varying means. In the present instance, a fluid pressure governed means is employed, and comprises a vertical cylinder |20, mounted upon the bracket I2I, a plunger |22 tted in the lower end of the cylinder |20, a weighted sleeve |23 tted and movable vertically on the cylinder |20, a spring |24 interposed between the plunger |22 and the upper end of the sleeve |23. The sleeve I 23 may be adjustably weighted by the divided rings |25 to determine the pressure which the compressor is to maintain. The cylinder I 20 is connected below the plunger |22 with the discharge pipe 39 by the pipe |26. The sleeve |23 is connected by the head |21, the pivotally mounted pin |28, the rod |29, the pivotally mounted pin I 30, the angular rocker |3| pivotally mounted on the pin |32, supported by the bracket |33, the pin |34 and the rod |35, the pivotally supported pin |36 and the angular rocker I 31 pivotally mounted on the pin |38 supported by the bracket |33, the pivotal pin |39, and the rod |40 to the floating lever I|4 with the pin II9, and to the floating lever with the pin |36, rod I4I, pivotal pin |42, angular rocker |43 pivotally mounted on the pin |44 supported by the bracket 33, pivotal -pinf |45,`rod .|46 and the pive otal.pin.:|00'. -The oatingleversz85 'and II4 and associated Vmechanism* andcontrols operated by.

turn, decreases the delivered capacity of the compressor, while a decrease in thepressure Ain'tlie pipe 39,'causes the pin |28 to fallfandf with it the pilot valves I 03;. 1I, whichl in turn causes the pistons 53, 51, to rise,-decrease' the..volume of the supplemental clearance, and increase the'fdeliwered capacity of the compressori: Accordingly, means are provided for. moving," controllingfttie extent of movement, stopping, and locking the mechanism in positions corresponding yto the movement of iluid pressure. governed 'regulating means to gradually lVary Athe".sup'plem'enta'lclearance volume in response to gradualvariations in' demand, and in thefpressure inafor-'examplepthe delivery pipe, in one-compression compartment,

or', in a plurality-'of compression compartments.'

'Ihe pointer v|41 isxedly -mounted lupon' any' rod as for example, the rod E0, to cooperate with the scale |48 which is shownlmounted upon the head 66, to indicate thelcapacity delivered bythe.

compressor at all rates of ,delivery withinfthe lime.

its of variation, and with constant inlet and dis` charge pressures. The scale |48 may also -read in percentage of clearance." 'I'he'frame '|49 mayl contain a curve sheet from which the actual capacity delivered may be read from the percentage of clearance and the ratio of compression calculated from the ratio of the discharge pressure read upon the ypressure gage |50 connected with the discharge pipe 39 by the pipe I5| and the inlet pressure read from the pressure gage |52 connected with the inlet pipe I6 by the pipe |53, and corrected for temperature by readings from the thermometer |54 placed in the inlet pipe I6, as a result of the phenomena of compression and delivery as obtained in compressors constructed and operated according to my invention. Accordingly, means are provided not only to operate the supplemental clearance varying means, but also, to vary gradually the clearance volume supplemental to the normal clearance volume, means to control the extent of the said gradual variations of the lsaid supplemental clearance volume, to consequently vary thedelivered capacity and power with variations in demand, in response to variations in pressure, and means for indicating the same, all by an infinite number of slight or imperceptably minute additions or reductions, progressively increasing as by increments, or progressively decreasing as by decrements, which may be characterized by gradual slopes or curves, in one compression compartment, or in a plurality of compression compartments. V,

Referring to Fig 4, a modified operation of the pistons 53, 51 isshown. In this arrangement of my invention, the piston 53 is operated by the auxiliary piston |55, provided with the piston rings |56, |51, xedly mounted upon the rod 56,' and disposed within the cylinder |58, mounted upon the distance piece |59 which serves jointly as heads for the cylinders 49, and |58, and which is provided with the stufling boxes |60, |6| and the stuiiing box glands |62, |63 respectively. The pilot valve |64 is provided with the full diameter sections |65, |66, the reduced diameter section 61, and the central passage |68, for operation in the pilot valve body |69, closed at its upper end with the head |10 and the stuffing box gland |1|, and at its lower end with the head |12, and mounted upon the bracket |13. The pipe |14 is supplied with a source of fluid under pressure as from the pipe 39, or from the pipe 89, and the pipes |15, |16 may either supply fluid under pressure or exhaust it, depending upon the position of the pilot valve |64. When the regulator pin |28 drops as a result of lowering pressure in the pipes 39, |26, the pin 99 and the pilot valve |64 also drop lto a position as shown, the floating lever 95 having moved about its fulcrum pin 96, and fluid is exhausted from the cylinder |58 through the pipe |15, the central passage |68 of the pilot valve |64, and the pipes |02, while at the same time, fluid under pressure flows from the pipe |14 around the reduced diameter section |61 of the pilot valve |64, and through the pipe |16 to lift the piston |55, the rod 56 and the piston 53.v Simultaneously, the piston rod 56 lifts the pin 96 and its end of the oating lever 95 about its new fulcrum pin |00 and lifts the pilot valve |64 to close the passages and pipes |15, |16, so no fluid ows in either, and the piston |55, as well as thepiston 53, are both locked in a new position. The

lifting of the pistons |55, 53, decreases the sup.

plemental clearance volume between the piston 53 and the end of the cylinder served by the passage 41 which increases the delivered capacity of the compressor, and again builds up the pressure in the pipe 39. When the pressure in the pipe 39 rises, the pins |28, 99, and the pilot valve |64 rise, resulting in the flow of fluid under pressure through the pipe |15, and the exhaust of fluid through the pipe |16, which lowers the pis- -tons |55, 53, and the rod 56, and the end of the iioating lever 95 with connecting pin 96 to again lock the pistons |55, 53 by way of closing the pipes |15, |16, from communication with the pipes |14, |0|. The lowering of the piston 53 increases the supplemental clearance volume in the cylinder 49 between the piston 53 and the cylinder and decreases the delivered capacity from this single end of the cylinder to prevent the pressure from rising substantially above the desired normal to be maintained in the pipe 39.

Likewise, the piston 51 is operated by the auxiliary piston |11, provided with the piston rings |18, |19, is iixedly mounted upon the rod 60 and disposed within the cylinder |80, mounted upon the distance piece 8| which serves jointly as heads for the cylinders |80, and which is provided with the stuffing boxes |82, |83, and the glands |84, |85 respectively. The pilot valve |86, provided with the full diameter sections |81, |88, the reduced diameter section |89, and central i passage |90, operates in the pilot valve body |9|, which is closed at its upper end with the head |92 and the stufling box gland |93, and at its lower end with the head |94 which is mounted upon the bracket |13. The pipe |95 is supplied with fluid under pressure as from a source such as the pipe 39, or from the pipe 89, and the pipes |96, |91 may either supply fluid under pressure, or exhaust it depending uponl the position of the pilot Vvalve |86;A When the' regulator pin |28 drops as a result of lowering pressure in the pipes 39, |26, the pin ||8 and the pilot valve |86 also drop to a position as shown, the floating lever ||4 having moved about its fulcrum pin 5, and uidv is exhausted from the cylinder |80 through the pipe |96, the central passage |90 of the pilot valve |86, and the pipes ||3, |02, while at the same time, fluid under pressure ows from the pipe |95 around the reduced diameter section |89 of the pilot valve |86, and through the pipe |91 to lift the piston |11, the rod 60 and the piston 51. Simultaneously, the piston rod 60 lifts the pin ||5 and its end of the floating lever ||4 about its new fulcrum pin |9, and lifts the pilot valve |86 to close the passages and pipes |96, |91 so no fluid iiows, and the piston |11, as well as the piston 51, are both locked in a new position. The lifting of the pistons |11 and 51 decreases the supplemental clearance volume between the piston 51 and the end of the cylinder served by the passage 48 which increases the delivered capacity of this end of the compressor similar to the other end of the compressor, and thus, again builds up the pressure in the pipe 39. When the pressure in the pipe 39 rises, the pins |28, I8, and the pilot valve |86 rise, resulting in the flow of fluid under pressure through the pipe |96, and the exhaust of fluid through the pipe |91, which lowers the pistons |11, 51, and the rod 60 and the end of, the oating lever 4 with connecting pin |5 to again lock the pistons |11, 51 by way of closing the pipes |96, |91, from communication with the pipes |95 and H3. 'I'he lowering of the piston 51 increases the supplemental clearance volume in the cylinder 5| between the piston 51 and the cylinder and decreases the delivered capacity from this second end of the plurality of compression compartments of the cylinder to maintain the pressure in the pipe 39 substantially constant, and to limit its variations from the desired normal pressure to a relatively small difference.

As the floating levers 95, ||4, are moved simultaneously by the pins |28, |00, 9, and as the movements of the pistons 53, 51, |55, |11 are required to close the pilot valves |64, |86, and the pipes |15, |16, and |96, |91 respectively, the movements of the supplemental clearance control pistons 53, 51, and the supplemental clearance volumes will always be the same and equal in the arrangement as shown. Whereas, I have described the above arrangement for synchronous operation of the supplemental clearance volume varying means simultaneously, it will be understood that many combinations are possible by way of changing the positions and lengths of the pilot valve sections, and the positions of the service pipes as they enter or leave the pilot valve bodies, and by operating the pins 99, ||8 selectively in slots arranged for operating the supplemental clearance piston 53 in sequence with the supplemental clearance piston 51 to effectl either successive or selective operation of the same in which any or all supplemental clearance volume controls may either antecede or supplement any other control. Accordingly, I have provided means for operating and controlling a plurality of supplemental clearance volume varying means gradually and continuously in a plurality of compression compartments in response to variations in the movements of the uid pressure governed regulating means, responsive to variations in the fluid pressure and in the demand, all of which may be characterized by gradual slopes or curves.

The passage |98, the coupling |99, and the passage 200 may be provided to interconnect the cylinder 49 with the cylinder 5| when the pistons 53, 51, as shown in Fig. 4 are in their extreme outward positions, to cause the air or gas to be circulated back and forth through the clearance cylinders 49, and 5I, and the passages 41, 48, from one end of the compression cylinder I to the other end to effect .complete unloading to zero capacity. Accordingly, I have provided means for gradually varying the delivered capacity from the full rated capacity down to a predetermined minimum delivered capacity by gradually varying the clearance volumes supplemental to the normal clearance volumes for each of the respective opposite ends of the cylinder I inversely with variations in demand, followed by complete unloading to zero delivered capacity without the requirement of additional valves such as pressure operated pistons, incidental cylinders and control mechanism for the same.

The piping 20|, connected with the head 18, may connect with the piping 202, connected with the head ||0, and the piping 203, with the discharge pipe 39 to prevent the building up of pressure, or the formation of vacuum in the cylinders 49, between the piston 53 and the head 18, and 5I between the piston 51 and the head I I0, in this arrangement of my invention to provide means for maintaining a relatively low net unbalanced resistance against the pistons 53 and 51.

Referring to Figs. 5 and 6, an arrangement of my invention is shown in which electric power ,is used in the means for operating the supplemental clearance volume varying means, the control of which is similar to that used in the fluid pressure;

operated arrangements above described. In this' arrangement, the piston rod 56 is threaded as at 204 where it extends beyond the gland 205 of the stuiling box 206 formed into the head 201, and slotted as at 208 along the threaded section 204 to prevent rotary motion of the rod 56 as it slides over the key 209, which is also mounted in the head 201. Likewise, the piston rod 60 is threaded as at 2I0 where it extends beyond the gland 2|| of the stuffing box'2 I2 formed into the head 2I3, and slotted as at 2I4 to prevent rotary motion. of the rod, 60 as it slides over the` key 2 I5 which is mounted in the head 2 I3. The internally threaded flanged collar 2|6 is disposed in the head 201, and retained in position by the head 2I1 and by the bearings 2I8, 2| 9 which serve as both bearings and as'thrust bearings. Also, the internally threaded flanged collar220 is disposed in the head 2I3 and retained in position by the head 22 I, and by the bearings 222, 223 which serve as both bearings and as thrust bearings. The worm gear wheel 224 is xedly mounted upon the flanged collar 2|6 and is operated by the worm 225 which is lxedly mounted upon the shaft 226 and retained in position by the head supports and bearings 221, 228. The worm gear wheel 229 is xedly mounted upon the internally threaded flanged collar 220 and is operated by the worm 230 which is xedly mounted upon the shaft 23| and retained in position by the bearings and supports 232, 233. The shafts 226 and 23| are interconnected by the pin coupling 234 so that the rods 56, 60, may move due to expansion or contraction of the compressor cylinder I without straining the parts or changing their angular relationship with respect to each other as they are driven by the auxiliary reversible electric motor 235, which is mounted upon the bracket 236, and energized by the source of electric supply 231.

The oating lever 238, similar to the floating levers 95, ||4, is pivotally mounted upon the rod 60 by the pin 239, and at its opposite end it is connected pivotally by the pin 240 to the rod |29 of the. fluid pressure governed regulator previously described, and is again jointly operated and controlled by the movement -of either or both of contact arcs 248, 249, mounted upon the insulatedl member 250, or it may bridge over and vcomplete an electric circuit. between the contact arcs 25|, 252, mounted upon the insulated member 253, and the insulated members 250, 253 may be adjustably mounted upon an extension 254 of the bracket 246 by the bolts 255. When the pressure in the pipes 39, |26 rises, the fluid pressure governed regulator lifts the pin 240 and its end of the floating lever 238 operating around,

the fulcrum point 239, and movesdthe conducting bridge 241 of the switch 244 to bridgeo'ver the arc contacts 248, 249, and completes an electric circuit from the source of electric supply through the lead 256, switch 251, switch point 258, lead 259, contact 248, bridge 241.contact 249, lead 260, contact points 26|, 262, of Athe spring operated limit switch 263, adjustably mounted upon the bracket 264 by the bolt 265, lead 266, clockwise rotation of the motor 23,5,

lead 261 back to the source of supply 231. .Clockwise rotation of the motor 235 rotates, the shaft 23|, coupling 234, shaft 226, worms 230, 225, Worm gear wheels 229, 224, and internally threaded flanged collars 220, 2 I6 respectively, thus causing the rods 60, 56, and attached pistons 51 and 53 to slide so that the pistons 51, 53, recede from the heads 2I3, 201, and increasegradually the supplemental clearance volumes in the cylinders 5|, 49, serving the cylinder I through the passages 48, 41 respectively, and gradually decrease the delivered capacity and, power of the cylinder I. At the same time such movement of the pistons 51, 53, and the rods 60, 58, are equal, as they are geared together, causing the pin 239 end of the floating lever 238 to move about its fulcrum pin 240 and in turn move the switch 244 and attached bridge 241 to break the circuit between the contact arcs 248, 249 and stop further .movement of the motor 235, pistons 51, 53, and

interconnecting mechanism. Conversely, a drop inv pressure in the pipes 39, |26, causes alowering of the pin 240 and its end of the oatinglever 238, moving around the fulcrum point 239, and moves the conducting bridge 241 of the switch 244-to bridge over the arc contacts 25|, 252, and completes an electric circuit from the source of electric supply through the lead 256, switch 251, switch point 258, lead 259, lead 268, contact arc 25|, bridge 241, contact arc 252, lead 269, spring operated limit switch 210, adjustably mounted upon the bracket 264 by the bolt 21|, contact points 212, 213, lead 214, counter clockwise rotation of the motor 235, and lead 261 back to the source of supply 231. tion of the motor 235 rotates the shaft 23|, coupling 234, shaft 226, worms 230, 225, worm gear wheels 229, 224, and internally Vthreaded flanged collars 220, 2| 6 respectively, thus caus- Counter clockwise rotaplemental clearance volumes in the cylinders 5|,

43, serving the cylinder I through the passages 48, 41 respectively, and gradually increase the delivered capacity 'and power of the cylinder At the same time, such movement of the pistons 51, 53, and the rods 60, 56, causes the pin 239 end of the floating lever 238 to move about its fulcrum p-oint 240 and in turn move the,switch 244 and attached bridge 241 to neutral position and to break the circuit between the contact arcs 25|, 252, and stop further movement of the motor 235, pistons 51, 53, and interconnecting mechanism, following which repeated actions occur in the movements of the fluid pressure governor and the oating lever 238 to continuously control the direction of rotation and the duration of rotation of the motor 235, the direction of travel, and the extent of travel of the pistons 51, 53 accordingly as. will be understood, to gradually vary continuously the clearance volumes supplemental to the normal clearance volumes simultaneously and equally in each end of the cylinder I in response to variations in pressure, caused by variations in demand, and to vary the delivered capacity and power gradually, progressively increasing the same as by increments, or, progressively decreasing the same as by decrements, which may be characterized by gradual slopes or curves. Whereas, I have shown and described a plurality of controls serving a plurality of compression compartments, it will be understood that by disiand driven mechanism,

connecting the coupling 234, the operation and control of only the piston 51 will be effected in the single compression compartment of the cylinder I served by the passage 48. The iioating lever 238 is provided with the extension 215 to operate the arm 2,16 of the limit switch 263 and stop the motor 235 when the pistons 51, 53, have reached their most extreme outward position furthermost from the headsv 2|3, 201 respectively, whereupon, there is now only one direction of travel desired and that is toward the heads 2|3, 201, and this movement is obtained by reverse rotation of the motor 235, the extreme travel of which is limited by the cooperation of the extension 211 of the floating lever 238 which operates the arm 218 of the limit switch 210 to stop the motor.235 and to prevent straining of the motor The limit switches 263, 210 may be adjustably positioned by the bolts 265. 21| respectively to limit the control of the variation of movement of the supplemental control pistons 53, 51, to any desired limits of capacity' variation delivered by the compressor cylinder I. The switch 251 may be operated manually by the member 219, or automatically such as by an electromagnetic member 280, energized by the leads 28|. 282, to render control by` the fluid pressure responsive governor and the floating lever 238 uneiectual, and to unload the compressor completely by throwing the switch 251 from' the switch point 258 to the switch point 283 to operate the auxiliary motor 235 in clockwise rotation and move the pistons 51, 53, to their extreme outward positions, and thus open the passages |98, |99. 200,7to circulate fluid back and forth in the cylinder I. After the motor 6 is ready, or again ready to take the load', the switch 251 may beh returned to the switch point 258 to again restore the automatic control by the fluid pressure regulator and floating lever 238.

Referring to Fig. 7, an arrangement is shown of my invention which is similar in most respects to the arrangement shown in Fig. 5 and 6, but in which two pistons are disposed within each supplemental clearance control cylinder in lieu of the arrangement shown in Figs. 5 and 6. In the arrangement shown in Fig. 7, the cylinder 284, provided with the water jackets 285, is connected with the cylinder I by the passage 41, and the cylinder 286, provided with the water jackets 281, is connected with the cylinder I by the passage 48. The piston 288, provided with the piston rings 289, 290, is disposed within the upper end of the cylinder 284, and the piston 29|, provided with the piston rings 292, 293, is disposed within the lower end of the cylinder 284. The piston 288 is threaded in its central opening to t and operate upon the'threaded portion of the rod 294 between the midpoint 295 of the cylinder 284 and the passage 41 and the head 201,'whereas, the piston 29| is threaded in its central opening to iit and operate upon the oppositely handed threaded portion of the rod 294 between the' said midpoint 295 and the lower head 296, where the rod 294 is retained in position by the plate 291, the bearing 298, the collar 299 and the4 pin 300 which may xedly attach the co-llar 299 to the rod 294. The upper end of the rod 294 is xedly attached to the flanged collar 30| by the pin 302. 'Ihe rod 303 is retained in position by the heads 201, 296, and passes through the pis-tons 288, 29| in sliding tted relation to prevent rotation of the said pistons 288, 29|, as the rod 294 is rotated in either clockwise or counter clockwise rotation to cause the pistons to approach and meet at the central point 295 as a limit of travel in this direction, a minimum of supplemental clearance volume, and a maximum delivered capacity of its compression compartment, or to recede oppositely from the central point 295 upon opposite rotationv of the shaft 294, to graduallyv increase the supplemental clearance volume and gradually decrease the delivered capacity up to the limit of variation obtained as the pistons 288, 29| approach the heads 201, 296, respectively, and vice versa. Likewise, the piston 304, provided with the piston rings 305, 396, is disposed within the upper end of the cylinder 289, and the piston 301, provided with the piston rings 338, 309, is disposed within the lower end of the cylinder 286. The piston'304 is threaded in its central opening to t and operate` upon the threaded portion of the rod 3I0 between the midpoint 3I| of the cylinder 286 and the passage 48, and the head 2|3, whereas, the piston 301 is threaded in its central opening to t and operate upon the oppositely handed threaded portion of the rod-3I0 between the said midpoint 3|| and the lower head 3I2, arid retained in position by the plate 3 I3, the bearing 3 I4, the collar 3 I5 and the pin BIB which may xedly attach the collar 3I5 to the rod 3I0. The upper end of the rod 3I0 is xedly attached to the flanged collar 3|1 as by the pin 3|8. The rod 3|9 is retained by the heads 2I3 and 3|2 and passes through the pistons 304, 381, in sliding fitted relation to prevent rotation of the said pistons 304, 301, as the rod 3I0 is rotated in either clockwise or counter clockwise rotation to cause the pistons to approach and meet at the central point 3| as a limit of travel in this direction, a minimum of supplemental clearance volume, and a maximum delivered capacity of the compressor compartment, or to recede oppositely from the central point 3| I upon opposite rotation of the shaft 3| 0 to gradually increase the supplemental clearance volume and gradually decrease the delivered capacity up to the limit of variation obtained as the pistons 304, 301, approach the heads 213, 312, after which, the compressor is completely unloaded when the pistons 288, 291, 304, 301, are adjacent the heads 201, 296, 213,and 312 respectively, thus opening the passages 320, 321, at the respective upper and lower ends of the cylinders 284, 286, and the opposite ends of the cylinder I to. circulate air or gas back and forth through the passages 41, 48, between the opposite ends of the cylinder 1. In addition to the operating of the worms 225, 230, andthe worm Wheels 224, 229, attached to the respective rods 294, 310 by the pins 302, 318 respectively, to rotate the rods in either clockwise or counter clockwise rotation depending upon the direction of rotation of the motor 235, I provide as a part of the control mechanism, the worm 322 iixedly mounted upon the motor drive shaft 23|, the driven worm gear wheel 323, and the rocker arm 324, both lixedly mounted upon the shaft 325, with the key 326, the shaft 325 being suitably supported by the bracket 321. The rocker arm 324 is pivotally connected by the pin 328, the rod 329, and the pivotally mounted pin 330 with the rod 331 which slides in suitable openings in the extensions 332, 333, of the bracket 321, and which in turn is pivotally connected with the ioating lever 238 with the pin 334, thus giving motion to the pin` 334 and its end of the floating lever 238 in correspondence with reversals of direction of the motor 235, and in correspondence with the extent of movement and direction of movements of the pistons 288, 29|, 304, and 301.

Referring to Fig. 8 of my invention, the fluid pressure responsive governed regulator pin |28 is shown connected directly to the switch member 244 by the rod |29, andthe pin 243 for use in connection with such arrangements as desired in combinations in which the oating lever features of the particular control is not needed.

Referring to Figs. 9, 10, and 11, a modied form of my invention is shown in which the supplemental clearance volume is divided into a number of variable and unvariable fractional divisional parts of the total, and in which the variable divisional part of the total is arranged to antecede the unvariable divisional parts of denite predetermined fixed volume, and then supplement each such unvariable xed volume as successively made elfective, thus obt/aining combinations of varying volumes which vary gradually to any requirement between the limits of zero volume and the total combined volumes of Vthe variable and unvariable fractional divisions of the same, progressively increasing as by increments, or progressively decreasing as by decrements, which may be characterized by gradual slopes or curves.

Referring to Fig. 9, the cylinder 335 may contain a piston 336, similar to the piston 51, and be operated and controlled by the rod 331, similar to the rod 60, and be closed at its upper end by the head 338, similar to the head 213, and be connected to the cylinder 1 by the passage 339, similar to the passage 48. When the piston 336 moves from a position adjoining the head 338, it rst uncovers the passage 339, and then successively, the passage 340 and the clearance pocket 34|, passage 342 and a clearance pocket which is not shown but similar to the pocket 34|, passage 343 and pocket 344, passage 345 and passage 346, each with a pocket which is not shown, passage 341 and pocket 348, passage 349 and pocket 350, passage 35| and a pocket not shown, all the said pockets being of predetermined xed unvariable volume, and nally, the

passage 352 may interconnect with a similar passage in .another cylinder to permit the complete unloading of the compression compartments so-served, similar to that effected by passages 198, 199, 280, and passages 320, 321.

Referring to Figs. 10 and 1l of my invention, I provide in addition to the supplemental clearance volume cylinders 49, 51, the xed, unvariable volume, supplemental clearance pocket 353, controlled by the valve 354, which is opened by the spring 355 and closed by the pressure of a fluid which flows through the pipe 356 acting to push the piston 351 to close the valve 354. and conversely, the exhaust of fluid through the pipe 356 permits the spring 355 to act and open the valve 354. A valve, similar to valve 354, and fixed volume clearance pocket 358, similar to the pocket 353, are disposed within the housing 359 at the opposite end of the cylinder 1, and controlled by flow of, or exhaust of iluid through the pipe 360, similar to the customary manner as used in the conventional type of compressors operating and controlled by the well known step by step clearance pocket control. According to my invention, the unvariable pocket 353 is anteceded in its operation by the continuous operation of the variable gradual varying supplemental clearance control cylinders 49, 51, and the pistons 53, 51, which are continuously operated to gradually vary the volume of supplemental clearance from any amount to any other amount for vsmall variations between the limits of zero volume and a volume equal to the volume of the unvariable pocket 353 which is next made effective, and simultaneously, the variable supplemental clearance Volume in the cylinders 49, 5|, controlled by the pistons 53, 51, continuously supplement the volume of the unvariable volume pocket-353 from their zero volume, gradually adding supplemental clearance to the volumeV of pocket 353, up to a volume equal to the additional volume of the pocket 358 which is next made effective, and simultaneously again, the variable supplemental clearance volume in the cylinders 49, 5| and controlling pistons 53, 51 supplement from their zero volume the unvariable volume of the sum of the two fixed volume pockets 353, 358 by gradually increasing continuously the effective volume by volumes varying from zero up to the maximum available volume of the variable divisional parts 49, 51, to gradually increase the clearance volume supplemental to the normal clearance volume of the cylinder l progressively increasing as by increments, and conversely, by reverse operation effected by theI control mechanism, progressively decreasing the said net total of all the supplemental clearance volumes as by decrements, by decreasing the effective volume in the cylinders 49, 51, after which the pocket 358 is cut out of operation, then the effective volume in the cylinders 49, 51 is again decreased, after which, the pocket 353 is cut out of operation, and then again, the effective volume in the cylinders 49, and 5| is gradually reduced from a volume equal to the volume of the pocket 353 by decrements, as required, to effect the correct supplemental clearance volume to deliver the desired capacity, down to the limit of zerovol- Lune and a maximum delivered capacity of the compressor. The operation of the iiuid pressure governed regulator and other similarly numbered parts, is the same as described by reference to the preceding figures of my invention. In this arrangement of ,my invention, the regulator controlled pin 128 is connected to the member 36| by the rod |23, and pivotally mounted pin 362, to move the member 36| pivotally about its sup-v porting pin 363 which in turn is mounted upon the bracket 364 and the compressor frame 4. The member 36| is provided with the slot 365 which cooperates with the pin 366 attached to the .rod 361, to operate the interconnecting pin 368, the rod 363, and attached pilot valve 316, by compressing the returning spring 31|, operating between the head 312 and the pilot valve 316. Also, the member 36| is provided with the slot 313 which cooperates with the pin 314, attached to the rod 315, to operate the interconnecting pin 316, the rod 311, and attached pilot valve 318 by compressing the returning spring 313, operating between the head 312 and the pilot valve 318.

The member 36| also operates the periodic cyclical cam 366 in rotational movement about the pin 36|, suitably supported by the bracket 382, and the frame 4, through the rod 383, and the pivotally mounted pins 384, 385. The periodic cyclical cam 386 is therefore moved in response to movements of the fluid pressure governed regulator pin |28. When the pressure in the pipes 33, |26, is the lowest, the pin |28 is in its lowest position, and the roller 386, pivotally mounted in rolling relationship with the oating lever 238, by the pin 381, rests upon the smallest radial part of the section 388 of the cam 386, thus effecting a bridging over of the contact arcs 25|, 252, by the bridge 241, counter clockwise rotation of the motor 235, and a reduction of the supplemental clearance volume in the cylinders 43, 5| to zero, thus increasing the delivered capacity .of the cylinder to its maximumcapacity. Such maximum delivered capacity increases the pressure in the pipes 33, |26, and causes the uid `pressure governed pin |26 to gradually rise, ef-

Iecting a clockwise rotating movement of the member 36|, counter clockwise rotating movement of the cam 386, and a gradual increasing in the effective length of the radii of the cam sec- Ation 388,- and a gradual lifting of the roller 3,66,

and its end of the oating lever 238 to gradually increase the clearance in the cylinders 43, 5|, to effect a balance between delivered capacity and demand, which is reflected by the pressure in the pipes .33, |26. As the pressure in the pipes 33, |26 continues to rise, the cam 386, and the member 36|, continue to move to increase the supplemental clearance volume in the cylinders 43, 5|, to their maximum volume, reached. when the roller 386 is rolling upon the greatest length radius of the section 388 of the cam 386, whereupon simultaneously, the member 36| in coop'- eration with the slot 365, and the pin 366, picks up the movement and liitsv the pilot valve 316 to bring into placeits reduced diameter sectionc363 toeil'ect communication between the pipes 356 and 336, to cause exhaust of fluid from above the piston 351, and the valve 354 to open, and make effective the unvariable supplemental clearance volume of the pocket 1 353, and the roller 366 has dropped to the shortest radius of the cam section 33|, and reduced the effective volume of the supplemental clearance cylinders 43, 5| again to zero value for the instant, following which, thecam 386 continuesto-move further in response to further upward movement ot the governor pin |28 to gradually increase the effective supplemental clearance volume in the cylinders 43, 5|, to gradually decrease the delivered capacity from the cylinder progressively as by decrements up to the limit of capacity reduction effected by the section 33| ot the cam 386, when simultaneously, the member 36|, in cooperation .with the s1ot'313, and the pin 314, picks up the movement, and liits the pilot valve 318 to bring into place its reduced diameter section 332 to eiect communication between the pipes 366 and 336, to cause exhaust of uid from controlling a piston similary to the piston 351, which also makes eiective thevolume of the unvariable supplemental clearance volume of the pocket 358, and again, the roller 386 has fallen to the shortest radius of the cam section 333, and rc-duced the effective volume of the supplemental Vclearance cylinders 43, 5|, to a zero value for the instant, and a total eiective volume represented by the sum of the volumes of the pockets 353, 358, following which the cam 386 continues to move further in response to further upward movement of the governor pin |28 to gradually increase 'the eiiective supplemental clearance volume in the cylinders 48, 5|, to gradually decrease the capacity delivered from the cylinder until the limit of minimum delivery is reached with maximum available total eil'ective supplemental clearance volume. Conversely, with a falling pressure in the pipe 33, |26,the eiective volume of the cylinders 43, 5|, is gradually reduced to their zero value, then the pocket 358 is made uneffective by the ow of iluid through the pipe 334, and pipe 366, and the volume of the cylinders 43, 5|, Vis Vagain a maximum for the instant, then gradually decrease to zero value, when the pocket 353 is made uneiective by the ilow lof uid through the pipe 334, and the pipe 356, and the volume o1' the cylinders 43, 5| is again made a maximum, after which the effective volume of the cylinders 43, 5|, is gradually reduced until the limit is reached at zero value when the maximum delivered capacity of the compressor cylinder I is again effective. Thus, the capacity, and power, are varied progressively as by increments, or progressively as by decrements, exactly to any requirement between the limits of the maximum and minimum capacity in response to variations in the pressure, effected by varying the effective volume of the supplemental clearance progressively'as by decrements, or progressively as by increments, exactly to any requirement between the limits of minimum and maximum effective supplemental clearance volume, and vice versa. It will be understood that in the particular arrangement oi.' variation of the variable and unvariable supplemental clearance volumes, the

operating of the unvariable volumes by fluid pressure, and the operating of the variable volumes by electric power is merely for the purpose of illustrating and describing one combination, and that many other .combinations are possible in accordance wth the principles of my invention.

In this arrangement of my invention, the pointer 335, suitably attached to the member 36|, is similar to the pointer |41, and the scale 336, suitably attached to the bracket 364, is similar to the scale |48, and their operation and use are the same as previously described.

Referring to Fig. 12, an alternate arrangement is shown in which the bore of the cylinder I may be extended as into the head plate 331, provided with the water jacket 338, to contain the supplemental clearance volume varying means such as the piston 333, provided with the piston rings 466, 46|, and the rod 462, to be operated and controlled in a similar manner as the pistons 53, 51, above described. The passage 463 corresponds to the |38, |33, 266, and the passage 464 may correspond to the passages connecting with pipes 19, or Ill, or with the pipes 20|, 203 as will be understood from the accompanying drawings and the pertinent description.

Whereas I have described my invention by reference to specic'embodiments thereof, it will be understood that many modifications and changes may be made without departing from the spirit of the invention.

I claim:

1. In a variable capacity compressor, the combination of a cylinder comprising a compression compartment, a piston reciprocable therein, power operated means for operating the said piston, inlet and discharge valves and openings, and means for varying the clearance volume in indeinite extent by increments or decrements supplemental to the normal clearance volume in response to variation of output of the compressor.

2. In avariable capacity compressor, the combination of a cylinder comprising a compression compartment, a piston reciprocable therein, power operated means for operating the said piston, inlet and discharge valves and openings, and continuously operating means for varying the clearance volume in indefinite extents by increments or decrements supplemental to the normal clearance volume in response to variations of output of the compressor.

3. In a variable capacity compressor, the combination of cylinder means comprising a plurality of compression compartments, piston means reciprocable therein, power operated means for operating the said piston means, inlet and discharge valves and openings, and means effective throughout the entire travel of each of the said piston means for varying the clearance volume in indeinite extents by increments or decrements supplemental to each normal clearance volume in response to variations of output of the compressor.

4. In a variable capacity compressor, the combination of cylinder means comprising a plurality of compression compartments, piston means reciprocable therein, power operated means for operating the said piston means, inlet and discharge valves and openings, and continuously operating means for varying the clearance volume in indefinite extents respectively supplemental to each normal clearance volume responsive to variations of output of the compressor.

5. The combination of a device, comprising cylinder means, piston means reciprocable therein, means for operating the said piston means, valve and opening means, and continuously operating means for varying the clearance volume supplemental to each normal clearance volume by progressively increasing indeiinite increments or progressively decreasing indeilnite decrements the said supplemental clearance volumes in response to variations of output of the compressor as by decrements.

6. In a variable capacity compressor, the combination of cylinder means, piston means reciprocable therein, power operated means for operating the said piston means, inlet and discharge valves and openings, and means for varying the clearance volume supplemental to each normal clearance volume by progressively increasing indenite increments or progressively decreasing indenite decrements the said supplemental clearance volumes, to vary the delivered capacity and power continuously and gradually between predetermined fractional limits of capacity.

7. In a variable capacity compressor, the combination of cylinder means, piston means reciprocable therein, power operated means for operating the said piston means, inlet and discharge valves and openings, supplemental clearance volume varying means comprising an indenitely variable volumetric division and an unvariable volumetric division thereof, means for indefinitely varying the effective volume of the variable division thereof.

8. In a variable capacity compressor, the combination of cylinder means, piston means reciprocable therein, power operated means for operating the saidl piston means, inlet and discharge valves and openings, supplemental clearance volume varying means comprising variable and unvariable fractional volumetric divisions thereof, means for effecting combinations of the said fractional divisions thereof and for indefinitely varying the effective volume of the variable volumetric division thereof by increments or decrements to vary the total supplemental clearance volume in indefinite extents.

9. In a variable capacity compressor, the combination oi' a cylinder comprising one compression compartment, a piston reciprocable therein, power operated means for operating the said piston, inlet and discharge valves and openings, means for varying the clearance volume in indeflnite extents by increments or decrements supplemental to the normal clearance volume, and power means for operating the said supplemental clearance volume varying means.

10. In a variable capacity compressor, the combination of a cylinder comprising one compression compartment, a piston reciprocable therein, power operated means for operating the said piston, inlet and discharge valves and openings, means for varying the clearance volume in indeilnite extents by increments or decrements supplemental to the normal clearance volume, and electrical means for operating the said supplemental clearance volume varying means.

11. In a variable capacity compressor, the combination of a cylinder comprising one compression compartment, a piston reciprocable therein, power operated means for operating the s aid piston, inlet and discharge valves and openings, means for varying the clearance volume in indefinite extents by increments or decrements supplemental to the 'normal clearance volume, and uid pressure means for operating the said supplemental clearance volume varying means.

12. In a variable capacity compressor, the combination o! cylinder means, piston means reciprocable therein, power operated means for operating the said piston means, inlet and discharge valves and openings, means for operating and for varying the clearance volume in indefinite extents by increments or decrements supplemental to each -normal clearance volume, and means for controlling the operation of the said operating and supplemental clearance volume varying means in response to varying output of. the compressor.

13. In a variable capacity compressor, the

combination of cylinder means, piston means reciprocable therein, poweroperated means for operating the said piston means, inlet and discharge valves and openings, means for varying the clearance volume in indefinite extents by increments or decrements supplemental to each normal clearance volume, means for operating the said supplemental clearance volume varying means, and means for controlling the operation aooaere and the extent of operation of the said operating means and the said supplemental clearance volume varying means in response to variations of output of the compressor.

14. In a variable capacity compressor, the combination of cylinder means, piston means reciprocable therein, power operated means for operating the said piston means, inlet and discharge valves and openings, means for varying the clearance Volume in indennita extents by increments or decrements supplemental to each normal clearance volume, means for operating the said supplemental clearance volume varying means, fluid pressure responsive regulator means, and means jointly operated by the said iiuid pressure responsive regulator means and by the said supplemental volume operating and varying means for controlling the operation and extent of operation of the said operating means and the said supplemental clearance volume varying means.

15. In a variable capacity compressor, the combination of a'cylinder comprising a compression compartment, a piston reciprocable therein, power operated means for operating the said piston at a substantially constant rate of speed, inlet and discharge valves and openings, associated with the cylinder, and means to continuously and gradually vary the clearance volume, supplemental to the normal clearance volume of the cylinder, in accordance with the variations in demand of the output of the compl'eSSOI.

EVERE'IT W. SWARTWOUT. 

